This is a very interesting game. I already know hiragana mostly, so hopefully you can do a katakana one soon! A couple comments:
1. It would be nice to go to the next level without going back to the level menu...
2. I would prefer to press "enter" key after each character instead of "space-bar". If you're typing for real you would press enter anyways..space-bar seems awkward.
3. Maybe after all levels are mastered...you could do bonus levels with hiragana words?
 "Kana Warrior / かなウォリアー"){kind=icon}